Download the .xpr file and save it to your skins/confluence/media foler
Now click the link for the xml. You'll see a folder on that page called "color", click that and on the next page you'll see the Mediterranean.xml. Right click that and "save as". Save that to skins/confluence/color/

Restart XBMC, go to "system" -> "Appearance"
Look at the themes and color sections. Just toggle the arrow up on each until Mediterranean is displayed. The screen will refresh, and you're done.